Epsilon values calculated for an isochron

53077 X 10 B - -0.22073 x 6.54 x 10 and C = O.S 13078, ( Nd/ Nd is normalized to 0.7219 and / is time before the present, in Ga). Point (6) is for samples of 3.8 Ga residual mande from Collerson et al. (1991). It should be noted that both curves (3) and (5) use the data of Ctaouc-Long et at. (1984) for the Kambalda volcanics which are now known to be incorrect. The lower curve is for Australian shales from Allegre and Rousseau (1984) and is thought to approximate to the evolution of average continental crust through time. 

Values for CHUR are given in Table 6.3. It should be noted that different laboratories use different normalizing values for the Nd ratio and the 

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CaJ Epsilon values calculated for an isochron Epsilon values are frequently quoted for Sm Nd isochrons and are a measure of the difference between the initial ratio of the sample suite and CHUR at the time of formation, expressed in parts per 10 (see Figure 6.2). They are calculated from the expression... 

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